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Unisom Sleepgels Maximum Strength

Generic name: diphenhydramineDYE-fen-HYE-dra-meen ]
Brand names: Allergy (Diphenhydramine HCl), Allergy Relief (Diphenhydramine HCl), Banophen, Benadryl, Benadryl Allergy, ... show all 41 brands
Drug classes: Anticholinergic antiparkinson agents, Antihistamines, Miscellaneous anxiolytics, sedatives and hypnotics

Medically reviewed by on Aug 1, 2023. Written by Cerner Multum.

What is Unisom Sleepgels Maximum Strength?

Unisom Sleepgels Maximum Strength is an antihistamine that is used to treat sneezing, runny nose, watery eyes, hives, skin rash, itching, and other cold or allergy symptoms.

Unisom Sleepgels Maximum Strength is also used to treat motion sickness, to induce sleep, and to treat certain symptoms of Parkinson's disease. This medicine sleep aid medicine is not for use in children younger than 12 years old.

There are many brands and forms of diphenhydramine available. Not all brands are listed on this leaflet.

Unisom Sleepgels Maximum Strength may also be used for purposes not listed in this medication guide.

Unisom Sleepgels Maximum Strength side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Unisom Sleepgels Maximum Strength may cause serious side effects. Stop using Unisom Sleepgels Maximum Strength and call your doctor at once if you have:

  • severe drowsiness; or

  • painful or difficult urination.

Side effects such as dry mouth, constipation, and confusion may be more likely in older adults.

Common side effects of Unisom Sleepgels Maximum Strength may include:

  • drowsiness;

  • dry eyes, blurred vision;

  • dry mouth, nose, or throat;

  • decreased urination;

  • constipation;

  • feeling restless or excited (especially in children); or

  • day-time drowsiness or "hangover" feeling after night-time use.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Use Unisom Sleepgels Maximum Strength exactly as directed. Taking too much Unisom Sleepgels Maximum Strength can lead to serious heart problems, seizures, coma, or death.

Do not use this medicine to make a child sleepy. Unisom Sleepgels Maximum Strength sleep aid medicine is not for use in children younger than 12 years old.

Before taking this medicine

You should not use Unisom Sleepgels Maximum Strength if you are allergic to it.

Ask a doctor or pharmacist if this medicine is safe to use if you have ever had:

  • an enlarged prostate or urination problems;

  • asthma, chronic obstructive pulmonary disease (COPD), or other breathing disorder;

  • glaucoma; or

  • a thyroid disorder.

Ask a doctor before using this medicine if you are pregnant or breastfeeding. Unisom Sleepgels Maximum Strength may slow breast milk production.

How should I take Unisom Sleepgels Maximum Strength?

Use exactly as directed on the label, or as prescribed by your doctor. Unisom Sleepgels Maximum Strength is only for short-term use until your symptoms clear up.

Taking too much Unisom Sleepgels Maximum Strength can lead to serious heart problems, seizures, coma, or death.

Always follow directions on the medicine label about giving Unisom Sleepgels Maximum Strength to a child. Do not use the medicine only to make a child sleepy. Death can occur from the misuse of antihistamines in very young children.

For motion sickness, take Unisom Sleepgels Maximum Strength 30 minutes before you will be in a situation that causes you motion sickness (such as a long car ride, airplane or boat travel, amusement park rides, etc). Continue taking this medicine with meals and at bedtime for the rest of the time you will be in a motion-sickness situation.

As a sleep aid, take Unisom Sleepgels Maximum Strength within 30 minutes before bedtime.

You must chew the chewable tablet before you swallow it.

Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Remove an orally disintegrating tablet from the package only when you are ready to take the medicine. Place the tablet in your mouth and allow it to dissolve, without chewing. Swallow several times as the tablet dissolves.

Call your doctor if the condition you are treating with Unisom Sleepgels Maximum Strength does not improve, or if you have a fever with a headache, cough, or skin rash.

Do not use Unisom Sleepgels Maximum Strength for longer than 2 weeks to treat sleep problems, or longer than 7 days to treat cold or allergy symptoms.

Unisom Sleepgels Maximum Strength can affect the results of allergy skin tests. Tell any doctor who treats you that you are using Unisom Sleepgels Maximum Strength.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Since Unisom Sleepgels Maximum Strength is used when needed, you may not be on a dosing schedule. Skip any missed dose if it's almost time for your next dose. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of diphenhydramine can be fatal.

Overdose symptoms may include vomiting, confusion, severe drowsiness, ringing in your ears, no urination, very dry eyes and mouth, dilated pupils, fast heartbeats, tremor, agitation, hallucinations, or seizure.

What should I avoid while taking Unisom Sleepgels Maximum Strength?

Avoid driving or hazardous activity until you know how Unisom Sleepgels Maximum Strength will affect you. Your reactions could be impaired.

Drinking alcohol can increase certain side effects of diphenhydramine.

Ask a doctor or pharmacist before using any other medicine that may contain Unisom Sleepgels Maximum Strength. This includes medicines for sleep, cold/allergy symptoms, or anti-itch medicine used on the skin. Using too much this medicine may lead to a fatal overdose.

What other drugs will affect Unisom Sleepgels Maximum Strength?

Ask a doctor or pharmacist before using Unisom Sleepgels Maximum Strength with any other medicines, especially drugs that can cause drowsiness (such as opioid medication, sleep medicine, a muscle relaxer, or medicine for anxiety or seizures). Tell your doctor about all your current medicines and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

Popular FAQ

The maximum oral dose of diphenhydramine for adults is generally reported as 100mg for a single dose or no more than 300mg in 24 hours, but this can vary depending on what condition diphenhydramine is being used for, the salt of diphenhydramine used (there are two salts available in the US diphenhydramine citrate and diphenhydramine chloride), the age of the person, how much diphenhydramine they have tolerated before, and if they are on any interacting medications. Taking too much diphenhydramine can be fatal. Continue reading

Mucinex products do not help to prevent or treat the COVID-19 virus itself, but might help relieve some of the symptoms of COVID, like chest congestion, cough, or headache. Select a product that targets only the symptoms you have. Continue reading

Increased blood pressure is not a typical side effect of diphenhydramine, a first-generation antihistamine that lowers the effects of histamines in your body. However, in rare cases, the drug may cause hypotension, or decreased blood pressure. This side effect is most likely to occur in people who are over the age of 60. Continue reading

Benadryl is quickly absorbed after oral administration and it starts to work within 30 minutes with peak effects reached within one to two hours. The effects of Benadryl last from four to six hours. Benadryl in the injectable form has a rapid onset of action. You will know when Benadryl starts to work because your allergy symptoms, such as congestion, runny nose, itchy eyes, or a skin rash, will start to feel better. Continue reading

Diphenhydramine can be used as a short-term sleep aid to help ease occasional sleep problems, such as when you have a cold or cough and it is preventing you from falling asleep. Older adults, children under age 16 and pregnant women should avoid taking diphenhydramine, as the risks to these groups may outweigh the benefits. Continue reading

Benadryl (generic name: diphenhydramine) is an antihistamine that causes sleepiness in most people. Some people use Benadryl to help with sleep or insomnia, but this should only be for short-term use. Do not use Benadryl to make a child sleepy. Contact your doctor if you or your child are having trouble with sleep. Continue reading

One of the most common side effects with Benadryl is drowsiness, but in some people it can have the opposite effect, known as paradoxical excitation. Instead of feeling sleepy,
you may experience excitation, agitation or insomnia (trouble sleeping), which might make your anxiety symptoms feel worse. This may be more common in young children. Continue reading

The difference between diphenhydramine hydrochloride and diphenhydramine citrate is that the salt used to bind the diphenhydramine, is different. For diphenhydramine hydrochloride the salt is hydrochloride and for diphenhydramine citrate the salt is citrate. This salt can change how quickly and effectively the diphenhydramine dissolves and is absorbed but once it is in the body it has no effect. Essentially 25 mg of diphenhydramine hydrochloride is equivalent to 38 mg of diphenhydramine citrate. Continue reading

More FAQ

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.